Mischievious, sacreligious, and supercede – did you notice that these words
were spelt incorrectly? On Friday the Telegraph ran a spelling quiz, but how
did you fare?

“I before E, except after C” – you probably learnt this simple rule in primary school and happily applied it to your writing, never doubting in its efficiency until, suddenly, you came across the word ‘eight’ and then ‘height’ and then the myriad of other exceptions that make this rule, arguably, pretty useless, as rules go.

This was certainly the view of the DfE, who in 2009 distributed a document to more than 13,000 primary schools affirming that this spelling mantra was no longer worth teaching.

However, the rhyme – which can be extended to make it slightly more helpful “I before E, except after C when the sound is EE” – was one of many that were taught to children to help with the difficult task of learning English spelling.

And difficult it certainly is. While it is estimated that 75 per cent of words in English take regular spellings, 25 per cent can be considered irregular and ambiguous at best.

Which makes it unsurprising that, in 2012, a survey by Mencap revealed that one in five adults can’t spell 'necessary', 'definitely' and 'separate', while a 2006 study from Collins dictionaries found that 'supersede' was the most commonly misspelt word on the Internet.

The word 'supersede' was, on Friday, enough to stump over 2000 Telegraph readers in ourspelling quiz.

When asked to pick out the incorrect spellings in a short sentence, many readers missed ‘superceded’ – selecting answers that didn’t include this option.

However, this wasn’t the only word to prove testing. Of the 14,092 respondents who had taken the quiz by the afternoon, only 24 per cent correctly identified ‘sacreligious’ as the incorrect spelling in a line up of ‘inoculate’, ‘consensus’ and ‘liquefy’.

The word should be spelt ‘sacrilegious’.

Similar to ‘superceded’, these words have something in common. According to Collins dictionaries, mistakes in spelling are often made because of our inclination to use our experience of other words; in the case of 'superseded', we might incorrectly use a ‘c’ because of the spelling of ‘precede’ and ‘concede’.

Likewise, the word ‘sacreligious’ looks correct because ‘religious’ is spelt correctly, while many would be inclined to spell ‘liquefy’ as ‘liquify’ due to the spelling of 'liquid'.

However, it isn’t simply our want to apply our knowledge of other words that makes spelling difficult. In a recent poll, OxfordWords found that the non-standard spelling of ‘mischievous’ proved to be more popular that the standard, with 53 per cent of voters saying they would spell it ‘mischievious’.

This echoes the Telegraph’s spelling quiz, which saw only 52 per cent of readers select the answer ‘mischievous’, while over 4,300 chose ‘mischievious’.

According to the Oxford English Dictionary, the alternative spelling could stem from the infrequent nature of the pronunciation ‘ee followed by vuhss’ in English, with the only other occurrence being ‘grievous’.

Apparently, it is due to this pronunciation that results in people replacing the end of the word with ‘ee followed by vious’ which is far more common and can be found in words such as ‘devious’ and ‘previous’.

Surely this is yet another case of don’t trust English spelling rules – in fact, maybe the only rule should be, don’t trust the rules?

However, it isn't all doom and gloom. Nearly 90 per cent of Telegraph readers were able to correctly identify the right word endings, whether that be '-ence' or '-ance' or, similarly, when to add a double consonant before adding '-ed'.